Magnetic assisted detection of magnetic beads using optical disc drives

The present invention is a method and apparatus for precise control of magnetic beads in an optical bio-disc. Embodiments of the present invention use electromagnets for precise control of the forces experienced by the magnetic beads. The use of electromagnets eliminates the need to design precise flow control mechanisms to keep beads in place. This is critical in the stage of washing in an assay, where beads attached to a bottom testing surface are separated from beads that are unattached. One embodiment contains a top electromagnet in a top layer of a bio-disc and a bottom electromagnet in a bottom layer of the bio-disc. Another embodiment is an apparatus of electromagnets that can be used to control the magnetic beads within the optical bio-disc. By adjusting the current flow to the electromagnets, precise control of beads can be accomplished.